1. Field of the Invention
The present invention relates to a charging system, and more particularly to a charging system for portable equipment.
2. Description of the Related Art
A portable telephone being charged by a prior-art contactless charging system based on electromagnetic induction, is shown in FIG. 3. The portable telephone 1 includes a secondary side coil 2, while a charger 3 includes a primary side coil 7. A user sets the portable telephone 1 on the charger 3 as shown in the figure and charges it for a predetermined time, period when the remaining battery capacity of the portable telephone 1 has become small, or when the portable telephone 1 is not used for a long time.
With the prior-art charging system as shown in FIG. 3, however, there is a spacing 5 between the primary side coil 7 and the secondary side coil 2, and induction cores 6 are kept apart, so that problems as mentioned below have been involved:
1. Since both the portable equipment and the charger need to include the cores made of a magnetic material such as metal, the weight and size of the portable equipment are increased.
2. Since the primary side coil and the secondary side coil are separate, even a very small deviation in the relative position between the coils exerts influence on a charging efficiency.
3. When a coin or an accessory article is accidentally held in the charger, the metal therein generates heat due to an induction current and forms a possible cause of a fire.
4. Since the charger is designed in adaptation to the geometries of the portable equipment, no charger can cope with multiple types of portable equipment.